With centrifugal pumps, in particular with heating circulation pumps of a small and medium construction size, it is part of the state of the art to control the pump rotational speed in dependence on the temperature of the fluid delivered. This is particularly the case in modern heating installations, where the pump control is separate and independent of the remaining control, apart from the set-up and the switching on/off of the supply voltage. The pump control registers the heating requirement of the heating installation by determining the temperature of the delivery fluid, and controls the pump speed accordingly. This is done in a manner such that, with an increased heating requirement, thus when the delivery fluid in the feed has a high temperature, the rotational speed and thus the pump power are increased, and with a lower temperature the rotational speed and pump power are lowered and thus reduced. However, it may be useful, make sense or be necessary to determine the temperature of the delivery fluid for other reasons. This is effected in the prior art typically by a temperature sensor.
Such a temperature sensor involves an additional component, wherein furthermore, additional evaluation electronics are required, which likewise create further costs. Moreover, the arrangement of a temperatures sensor creates a potential weak location, since the sensor must be brought into contact with the delivery fluid in a heat-conducting manner.